How safe is 12 word seed phrase?

Could you elaborate on the security of a 12-word seed phrase in the context of cryptocurrency wallets? Is it sufficient to protect users' funds from unauthorized access? Are there any vulnerabilities or best practices one should be aware of when using a 12-word seed phrase as a security measure? Furthermore, what are the steps one should take to ensure the safety of their seed phrase, and what are the consequences of losing or compromising it?